The correct answer is B) Steel. The reddish-colored oxide that forms on metal is known as rust, and it is a common occurrence on steel surfaces. This is due to the chemical reaction between iron (the primary component of steel) and oxygen in the presence of moisture, which leads to the formation of iron oxide, or rust. The other options are incorrect because aluminum forms a thin, protective oxide layer that is not reddish in color, chromium is resistant to corrosion and does not form a reddish oxide, and magnesium forms a white or gray oxide rather than a reddish one.